feat: 完成前端重构，采用 Ant Design 5 和完整测试体系

- 采用 Ant Design 5 作为 UI 组件库，替换自定义组件
- 集成 React Router v7 提供路由导航
- 使用 TanStack Query v5 管理数据获取和缓存
- 建立 Vitest + React Testing Library 测试体系
- 添加 Playwright E2E 测试覆盖
- 使用 MSW mock API 响应
- 配置 TypeScript strict 模式
- 采用 SCSS Modules 组织样式
- 更新 OpenSpec 规格以反映前端架构变更
- 归档 frontend-refactor 变更记录

frontend/src/types/index.ts

@@ -0,0 +1,73 @@
+export interface Provider {
+  id: string;
+  name: string;
+  apiKey: string;
+  baseUrl: string;
+  enabled: boolean;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface Model {
+  id: string;
+  providerId: string;
+  modelName: string;
+  enabled: boolean;
+  createdAt: string;
+}
+
+export interface UsageStats {
+  id: number;
+  providerId: string;
+  modelName: string;
+  requestCount: number;
+  date: string;
+}
+
+export interface CreateProviderInput {
+  id: string;
+  name: string;
+  apiKey: string;
+  baseUrl: string;
+  enabled: boolean;
+}
+
+export interface UpdateProviderInput {
+  name?: string;
+  apiKey?: string;
+  baseUrl?: string;
+  enabled?: boolean;
+}
+
+export interface CreateModelInput {
+  id: string;
+  providerId: string;
+  modelName: string;
+  enabled: boolean;
+}
+
+export interface UpdateModelInput {
+  providerId?: string;
+  modelName?: string;
+  enabled?: boolean;
+}
+
+export interface StatsQueryParams {
+  providerId?: string;
+  modelName?: string;
+  startDate?: string;
+  endDate?: string;
+}
+
+export class ApiError extends Error {
+  status: number;
+
+  constructor(
+    status: number,
+    message: string,
+  ) {
+    super(message);
+    this.name = 'ApiError';
+    this.status = status;
+  }
+}